Analysis of intermittent heating in a multi-component turbulent plasma

Abstract

Kinetic effects and turbulence are two phenomena that characterize the solar wind, and, therefore, kinetic models represent the best tool of investigation for this collisionless plasma. In this work, hybrid Vlasov-Maxwell simulations are performed to investigate the intermittent heating of the solar wind, in a two-dimensional multi-ion plasma composed by protons, alpha particles and fluid electrons. The numerical results show that particle distribution functions depart from the typical Maxwellian configuration under the effect of the turbulence. Both ion species develop temperature anisotropy, with respect to the local magnetic field, that increases during the development of the turbulent cascade. During the nonlinear evolution of the system, coherent structures (vortices and current sheets) appear in physical space, related to the intermittent nature of the magnetic field. Conditioned ion temperature distributions suggest that enhancements of ion temperatures are associated with stronger coherent structures, in agreement with recent solar wind data analyses.